1. Technical Field
The present invention relates to a bank structure, a method of forming a bank structure, a device, an electro-optical device and an electronic apparatus.
2. Related Art
As a method for forming wires and the like having a certain pattern and used for an electronic circuit, an integrated circuit and the like, photolithography has been widely used for example. The photolithography requires large-scale equipment, such as a vacuum apparatus, exposure apparatus and so on. In forming wires and the like having a certain pattern by using the above-described devices, complicated steps are required and the material use efficiency is about several percentages, i.e., most of the material needs to be wasted, leading to the problem of high manufacturing costs.
In contrast, a method has been proposed in which wires and the like having a certain pattern are formed on a substrate by using a droplet discharge method for discharging a liquid material in a droplet form from liquid discharge heads, i.e., a so-called ink jet method. This method is disclosed in Japanese Unexamined Patent Publications No. 11-274671 and 2000-216330 for example. In the ink jet method, a liquid material (functional liquid) for patterning is directly deposited on a substrate with being patterned, and thereafter the deposited material is converted to a pattern by heat treatment or laser irradiation. Therefore, this method offers advantages of simplifying processes significantly since photolithography steps are unnecessary, and of reducing the use amount of the material since a row material can directly be deposited on patterning positions.
In recent years, the density of circuits constituting devices has been increasing, and therefore further miniaturization and line-width reduction of wires have been also required for example. In a pattern forming method using the above-described droplet discharge method, since discharged droplets spread over a substrate after landing thereon, it is difficult to stably form minute patterns. Particularly if an electrical conductive film pattern is to be formed, formation of liquid swelling (bulge) resulting from the above-described spreading of droplets may cause defects, such as disconnection and short-circuit.
Therefore, another technique has been also proposed. In this technique, banks to define wire-formation regions are formed, and a functional liquid is discharged toward the wire-formation regions in the state in which the surfaces of the banks have been provided with lyophobicity. Thus, wires having a width smaller than the diameter during flight of the functional liquid discharged by the droplet discharge method are formed. By forming banks to define wire-formation regions as described above, even if part of the functional liquid is discharged on the upper surfaces of the banks, the functional liquid flows into the entire wire-formation regions since the upper surfaces of the banks have been provided with lyophobicity.
However, in recent years, the fact has been probed that contact of part of the functional liquid with the upper surfaces of the banks results in remaining of minute residues on the upper surfaces of the banks. If the functional liquid has electrical conductivity, for example, the residues also have electrical conductivity. Therefore, if the residues remain on the upper surfaces of the banks as described above, electrical characteristics of the wiring pattern itself and characteristics of a device employing the wires may change.